Abraham Lincoln is the only U.S. president to hold a patent. Indeed, in 1849, Honest Abe received U.S. Patent No. 6,469 for a “Manner of Buoying Vessels.” This patent envisioned a device for lifting boats over shoals. Lincoln was inspired during a trip traveling across the Great Lakes during which the steamboat ran aground on a sandbar. The captain of this boat improvised by emptying barrels and boxes and forcing them under the sides of the boat, thereby buoying it up. Prior to this, steamboats would discharge cargo and people when they got stuck in shallow water. This invention, however, was never put into practice.